U.S. patent application number 13/449424 was filed with the patent office on 2012-08-09 for synthesis of chabazite-containing molecular sieves and their use in the conversion of oxygenates to olefins.
Invention is credited to Mobae Afeworki, Guang Cao, Luc R.M. Martens, Machteld M. Mertens, Stephen N. Vaughn.
Application Number | 20120202954 13/449424 |
Document ID | / |
Family ID | 41569233 |
Filed Date | 2012-08-09 |
United States Patent
Application |
20120202954 |
Kind Code |
A1 |
Mertens; Machteld M. ; et
al. |
August 9, 2012 |
Synthesis of Chabazite-Containing Molecular Sieves and Their Use in
the Conversion of Oxygenates to Olefins
Abstract
In a method of synthesizing a silicoaluminophosphate molecular
sieve having 90%+CHA framework type character, a reaction mixture
is prepared comprising first combining a reactive source of
aluminum with a reactive source of phosphorus to form a primary
mixture that is aged. A reactive source of silicon and a template
for directing the formation of the molecular sieve can then be
added to form a synthesis mixture. Crystallization is then induced
in the synthesis mixture. Advantageously, (i) the source of silicon
comprises an organosilicate, (ii) the source of phosphorus
optionally comprises an organophosphate, and (iii) the crystallized
silicoaluminophosphate molecular sieve has a crystal size
distribution such that its average crystal size is not greater than
5 .mu.m. The molecular sieve can then preferably be used in a
hydrocarbon (oxygenates-to-olefins) conversion process.
Inventors: |
Mertens; Machteld M.;
(Boortmeerbeek, BE) ; Vaughn; Stephen N.;
(Kingwood, TX) ; Cao; Guang; (Princeton, NJ)
; Martens; Luc R.M.; (Meise, BE) ; Afeworki;
Mobae; (Lopatcong Township, NJ) |
Family ID: |
41569233 |
Appl. No.: |
13/449424 |
Filed: |
April 18, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12477750 |
Jun 3, 2009 |
8182780 |
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13449424 |
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61083775 |
Jul 25, 2008 |
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61083765 |
Jul 25, 2008 |
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61083760 |
Jul 25, 2008 |
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61083749 |
Jul 25, 2008 |
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Current U.S.
Class: |
526/75 |
Current CPC
Class: |
Y02P 20/584 20151101;
Y02P 30/20 20151101; C07C 2529/85 20130101; C07C 1/20 20130101;
Y02P 20/52 20151101; Y02P 30/42 20151101; B01J 2229/42 20130101;
B01J 29/85 20130101; B01J 29/90 20130101; Y02P 30/40 20151101; C01B
39/54 20130101; C07C 1/20 20130101; C07C 11/06 20130101; C07C 1/20
20130101; C07C 11/04 20130101 |
Class at
Publication: |
526/75 |
International
Class: |
C08F 10/02 20060101
C08F010/02; C08F 10/06 20060101 C08F010/06; C08F 2/00 20060101
C08F002/00 |
Claims
1.-16. (canceled)
17. A method of forming an olefin-based polymer product comprising:
(a) preparing a silicoaluminophosphate molecular sieve comprising;
(i) combining a source of phosphorus and a source of aluminum with
a liquid mixture medium to form a primary mixture, wherein said
source of silicon comprises an organosilicate and said source of
phosphorus comprises an organophosphate; (ii) aging the primary
mixture for an aging time and under aging in conditions sufficient
to allow homogenization of the primary mixture, physico-chemical
interaction between the source of phosphorus and the source of
aluminum, or both; (iii) adding a source of silicon,
N,N-dimethylcyclohexylamine organic template, and optionally
additional liquid mixture medium, to the aged primary mixture to
form a synthesis mixture; and (iv) inducing crystallization of a
silicoaluminophosphate molecular sieve, which exhibits 90% or
greater CHA framework type character, from said synthesis mixture
at a crystallization temperature, wherein the crystallized
silicoaluminophosphate molecular sieve has a crystal size
distribution such that its average crystal size is not greater than
5 .mu.m; (b) formulating said silicoaluminophosphate molecular
sieve, along with a binder and optionally a matrix material, into a
silicoaluminophosphate molecular sieve catalyst composition
comprising from at least 10% to about 50% molecular sieve; (c)
contacting said catalyst composition with a hydrocarbon feed under
conditions sufficient to convert said hydrocarbon feed into a
product comprising predominantly one or more olefins; (d)
polymerizing at least one of the one or more olefins, optionally
with one or more other comonomers and optionally in the presence of
a polymerization catalyst, under conditions sufficient to form an
olefin-based (co)polymer.
18. The method of claim 17, wherein the hydrocarbon feed is an
oxygenate-containing feed comprising methanol, dimethylether, or a
combination thereof, wherein the one or more olefins comprises
ethylene, propylene, or a combination thereof, and wherein the
olefin-based (co)polymer is an ethylene-containing (co)polymer, a
propylene-containing (co)polymer, or a copolymer, mixture, or blend
thereof.
19. The method of claim 17, wherein the crystallized
silicoaluminophosphate molecular sieve exhibits a Si/Al.sub.2 ratio
not more than 0.10 greater than the Si/Al.sub.2 ratio of the
synthesis mixture.
20. The method of claim 17, wherein said crystallization
temperature is between 150.degree. C. and 200.degree. C.
21. The method of claim 17, wherein the crystallized
silicoaluminophosphate molecular sieve has a crystal size
distribution such that the average crystal size is less than 2.0
.mu.m.
22. The method of claim 17, wherein the crystallized
silicoaluminophosphate molecular sieve has a crystal size
distribution such that the average crystal size is less than 1.2
.mu.m.
23. The method of claim 17, wherein the inducing step is done while
stirring.
24. The method of claim 17, wherein, within step (iii), said source
of silicon is combined with said primary mixture prior to adding
said at least one organic template.
25. The method of claim 24, wherein said primary mixture and said
source of silicon are combined to form a secondary mixture for a
time and under conditions sufficient to allow homogenization of the
secondary mixture, physico-chemical interaction between said source
of silicon and said primary mixture, or both, after which said at
least one organic template is combined therewith.
26. The method of claim 17, wherein the synthesis mixture and the
crystallized silicoaluminophosphate molecular sieve both exhibit a
Si/Al.sub.2 ratio less than 0.33.
27. The method of claim 17, wherein one or more of the following
are satisfied: the source of aluminum comprises alumina; the source
of phosphorus comprises phosphoric acid and an organophosphate
comprising a trialkylphosphate; the organosilicate comprises a
tetraalkylorthosilicate; and the at least one organic template
comprises N,N-dimethylcyclohexylamine.
28. The method of claim 17, wherein the organosilicate comprises
tetramethylorthosilicate, tetraethylorthosilicate, or a combination
thereof.
29. The method of claim 17, wherein step (iv) was accomplished
using seeds having a framework type of CHA, AEI, AFX, LEV, an
intergrowth thereof, or a combination thereof.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is related to, and claims priority
to, U.S. Ser. No. 61/083,775, U.S. Ser. No. 61/083,765, U.S. Ser.
No. 61/083,760, and U.S. Ser. No. 61/083,749, each filed on Jul.
25, 2008 and entitled, "Synthesis of Chabazite-Containing Molecular
Sieves and Their Use in the Conversion of Oxygenates to Olefins,"
the entire disclosures of each of which are hereby incorporated by
reference herein.
FIELD OF THE INVENTION
[0002] This invention relates to the synthesis of chabazite-type
containing molecular sieves and their use in the conversion of
oxygenates, particularly methanol, to olefins, particularly
ethylene and/or propylene.
BACKGROUND OF THE INVENTION
[0003] The conversion of oxygenates to olefins (OTO) is currently
the subject of intense research because it has the potential for
replacing the long-standing steam cracking technology that is today
the industry-standard for producing world scale quantities of
ethylene and propylene. The very large volumes involved suggest
that substantial economic incentives exist for alternate
technologies that can deliver high throughputs of light olefins in
a cost efficient manner. Whereas steam cracking relies on
non-selective thermal reactions of naphtha range hydrocarbons at
very high temperatures, OTO exploits catalytic and
micro-architectural properties of acidic molecular sieves under
milder temperature conditions to produce high yields of ethylene
and propylene from methanol.
[0004] Current understanding of the OTO reactions suggests a
complex sequence in which three major steps can be identified: (1)
an induction period leading to the formation of an active carbon
pool (alkyl-aromatics), (2) alkylation-dealkylation reactions of
these active intermediates leading to products, and (3) a gradual
build-up of condensed ring aromatics. OTO is therefore an
inherently transient chemical transformation in which the catalyst
is in a continuous state of change. The ability of the catalyst to
maintain high olefin yields for prolonged periods of time relies on
a delicate balance between the relative rates at which the above
processes take place. The formation of coke-like molecules is of
singular importance because their accumulation interferes with the
desired reaction sequence in a number of ways. In particular, coke
renders the carbon pool inactive, lowers the rates of diffusion of
reactants and products, increases the potential for undesired
secondary reactions and limits catalyst life.
[0005] Over the last two decades, many catalytic materials have
been identified as being useful for carrying out the OTO reactions.
Crystalline molecular sieves are the preferred catalysts today
because they simultaneously address the acidity and morphological
requirements for the reactions. Particularly preferred materials
are eight-membered ring aluminosilicates, such as those having the
chabazite (CHA) framework type, as well as aluminophosphates
(AlPOs) and silicoaluminophosphates (SAPOs) of the CHA framework
type, such as SAPO-34.
[0006] Chabazite is a naturally occurring zeolite with the
approximate formula Ca.sub.6Al.sub.12Si.sub.24O.sub.72. Three
synthetic forms of chabazite are described in "Zeolite Molecular
Sieves", by D. W. Breck, published in 1973 by John Wiley &
Sons, the complete disclosure of which is incorporated herein by
specific reference. The three synthetic forms reported by Breck are
Zeolite "K-G", described in J. Chem. Soc., p. 2822 (1956), Barrer
et al; Zeolite D, described in British Patent No. 868,846 (1961);
and Zeolite R, described in U.S. Pat. No. 3,030,181 (1962). Zeolite
K-G zeolite has a silica:alumina mole ratio of 2.3:1 to 4.15:1,
whereas zeolites D and R have silica:alumina mole ratios of 4.5:1
to 4.9:1 and 3.45:1 to 3.65:1, respectively.
[0007] In U.S. Pat. No. 4,440,871, the synthesis of a wide variety
of SAPO materials of various framework types is described with a
number of specific examples. Also disclosed are a large number of
possible organic templates, with some specific examples. In the
specific examples a number of CHA framework type materials are
described. The preparation of SAPO-34 is reported, using
tetraethylammonium hydroxide (TEAOH), or isopropylamine, or
mixtures of TEAOH and dipropylamine (DPA) as templates. Also
disclosed is a specific example that utilizes cyclohexylamine in
the preparation of SAPO-44. Although other template materials are
described, there are no other templates indicated as being suitable
for preparing SAPO's of the CHA framework type.
[0008] U.S. Pat. No. 6,162,415 discloses the synthesis of a
silicoaluminophosphate molecular sieve, SAPO-44, which has a CHA
framework type in the presence of a directing agent comprising
cyclohexylamine or a cyclohexylammonium salt, such as
cyclohexylammonium chloride or cyclohexylammonium bromide.
[0009] Silicoaluminophosphates of the CHA framework type with low
silicon contents are particularly desirable for use in the
methanol-to-olefins process. Thus, Wilson, et al., Microporous and
Mesoporous Materials, 29, 117-126, 1999 report that it is
beneficial to have lower Si content for methanol-to-olefins
reaction, in particular because low Si content has the effect of
reducing propane formation and decreasing catalyst
deactivation.
[0010] U.S. Pat. No. 6,620,983 discloses a method for preparing
silicoaluminophosphate molecular sieves, and in particular low
silica silicoaluminophosphate molecular sieve having a Si/Al atomic
ratio of less than 0.5, which process comprises forming a reaction
mixture comprising a source of aluminum, a source of silicon, a
source of phosphorus, at least one organic template, at least one
compound which comprises two or more fluorine substituents and
capable of providing fluoride ions, and inducing crystallization of
the silicoaluminophosphate molecular sieve from the reaction
mixture. Suitable organic templates are said to include one or more
of tetraethyl ammonium hydroxide, tetraethyl ammonium phosphate,
tetraethyl ammonium fluoride, tetraethyl ammonium bromide,
tetraethyl ammonium chloride, tetraethyl ammonium acetate,
dipropylamine, isopropylamine, cyclohexylamine, morpholine,
methylbutylamine, morpholine, diethanolamine, and triethylamine In
the Examples, crystallization is conducted by heating the reaction
mixture to 170.degree. C. over 18 hours and then holding the
mixture at this temperature for 18 hours to 4 days.
[0011] U.S. Pat. No. 6,793,901 discloses a method for preparing a
microporous silicoaluminophosphate molecular sieve having the CHA
framework type, which process comprises (a) forming a reaction
mixture comprising a source of aluminum, a source of silicon, a
source of phosphorus, optionally at least one source of fluoride
ions and at least one template containing one or more
N,N-dimethylamino moieties, (b) inducing crystallization of the
silicoaluminophosphate molecular sieve from the reaction mixture,
and (c) recovering silicoaluminophosphate molecular sieve from the
reaction mixture. Suitable templates are said to include one or
more of N,N-dimethylethanolamine, N,N-dimethylbutanolamine,
N,N-dimethylheptanolamine, N,N-dimethylhexanolamine,
N,N-dimethylethylenediamine, N,N-dimethylpropylenediamine,
N,N-dimethylbutylene-diamine, N,N-dimethylheptylenediamine,
N,N-dimethylhexylenediamine, or dimethyl-ethylamine,
dimethylpropylamine, dimethyl-heptylamine, and dimethylhexylamine.
When conducted in the presence of fluoride ions, the synthesis is
effective in producing low silica silicoaluminophosphate molecular
sieves having a Si/Al atomic ratio of from 0.01 to 0.1. In the
Examples, crystallization is conducted by heating the reaction
mixture to 170 to 180.degree. C. for 1 to 5 days.
[0012] U.S. Pat. No. 6,835,363 discloses a process for preparing
microporous crystalline silicoaluminophosphate molecular sieves of
CHA framework type, the process comprising: (a) providing a
reaction mixture comprising a source of alumina, a source of
phosphate, a source of silica, hydrogen fluoride and an organic
template comprising one or more compounds of formula (I):
(CH.sub.3).sub.2N--R--N(CH.sub.3).sub.2
where R is an alkyl radical of from 1 to 12 carbon atoms; (b)
inducing crystallization of silicoaluminophosphate from the
reaction mixture; and (c) recovering silicoaluminophosphate
molecular sieve. Suitable templates are said to include one or more
of the group consisting of:
N,N,N',N'-tetramethyl-1,3-propane-diamine,
N,N,N',N'-tetramethyl-1,4-butanediamine, N,N,N',N'-tetramethyl-1,3
-butanediamine, N,N,N',N'-tetramethyl-1,5-pentanediamine,
N,N,N',N'-tetramethyl-1,6-hexanediamine,
N,N,N',N'-tetramethyl-1,7-heptanediamine,
N,N,N',N'-tetramethyl-1,8-octanediamine,
N,N,N',N'-tetramethyl-1,9-nonanediamine
N,N,N',N'-tetramethyl-1,10-decanediamine,
N,N,N',N'-tetramethyl-1,11-undecanediamine and
N,N,N',N'-tetramethyl-1,12-dodecanediamine. In the Examples,
crystallization is conducted by heating the reaction mixture to 120
to 200.degree. C. for 4 to 48 hours.
[0013] U.S. Pat. No. 7,247,287 discloses the synthesis of
silicoaluminophosphate molecular sieves having the CHA framework
type employing a directing agent having the formula:
R.sup.1R.sup.2N--R.sup.3
wherein R.sup.1 and R.sup.2 are independently selected from the
group consisting of alkyl groups having from 1 to 3 carbon atoms
and hydroxyalkyl groups having from 1 to 3 carbon atoms and R.sup.3
is selected from the group consisting of 4- to 8-membered
cycloalkyl groups, optionally substituted by 1 to 3 alkyl groups
having from 1 to 3 carbon atoms; and 4- to 8-membered heterocyclic
groups having from 1 to 3 heteroatoms, said heterocyclic groups
being optionally substituted by 1 to 3 alkyl groups having from 1
to 3 carbon atoms and the heteroatoms in said heterocyclic groups
being selected from the group consisting of O, N, and S.
Preferably, the directing agent is selected from
N,N-dimethylcyclohexylamine, N,N-dimethyl-methylcyclohexylamine,
N,N-dimethyl-cyclopentylamine, N,N-dimethyl-methylcyclopentylamine,
N,N-dimethylcycloheptyl-amine,
N,N-dimethyl-methyl-cycloheptylamine, and most preferably is
N,N-dimethyl-cyclohexylamine. The synthesis can be effected with or
without the presence of fluoride ions and, in the Examples,
crystallization is conducted by heating the reaction mixture to
180.degree. C. for 3 to 7 days.
[0014] According to the present invention, it has unexpectedly been
found that the order of addition and relative homogenization of the
synthesis mixture components, as well as whether certain synthesis
mixture components are inorganic or organic, in
silicoaluminophosphate molecular sieve formulations can enhance
certain desirable properties, such as reducing the crystal size of
the product, while still maintaining an acceptable product yield.
Interestingly, the use of organic sources of silicon, and
optionally also phosphorus, as opposed to inorganic sources, can
facilitate a more intimate/reactive combination of synthesis
mixture components and appears to be a robust way to make the
synthesis mixture, preferably resulting in more desirable molecular
sieve products.
SUMMARY OF THE INVENTION
[0015] In one aspect, the invention relates to a method of
preparing a silicoaluminophosphate molecular sieve having a desired
crystal size, the method comprising: (a) combining a source of
phosphorus and a source of aluminum, optionally with a liquid
mixture medium, to form a primary mixture; (b) aging the primary
mixture for an aging time and under aging conditions sufficient to
allow homogenization of the primary mixture, physico-chemical
interaction between the source of phosphorus and the source of
aluminum, or both; (c) adding a source of silicon, at least one
organic template, and optionally additional liquid mixture medium,
to the aged primary mixture to form a synthesis mixture; and (d)
inducing crystallization of a silicoaluminophosphate molecular
sieve, which exhibits 90% or greater CHA framework type character,
from said synthesis mixture at a crystallization temperature,
wherein said source of silicon comprises an organosilicate and said
source of phosphorus optionally comprises an organophosphate, and
wherein the crystallized silicoaluminophosphate molecular sieve has
a crystal size distribution such that its average crystal size is
not greater than 5 .mu.m.
[0016] In another aspect, the invention relates to a method of
converting hydrocarbons into olefins comprising: (a) preparing a
silicoaluminophosphate molecular sieve according to the method of
the previous aspect of the invention; (b) formulating said
silicoaluminophosphate molecular sieve, along with a binder and
optionally a matrix material, into a silicoaluminophosphate
molecular sieve catalyst composition comprising from at least 10%
to about 50% molecular sieve; and (c) contacting said catalyst
composition with a hydrocarbon feed under conditions sufficient to
convert said hydrocarbon feed into a product comprising
predominantly one or more olefins.
[0017] In another aspect, the invention relates to a method of
forming an olefin-based polymer product comprising: (a) preparing a
silicoaluminophosphate molecular sieve according to the method of
the first aspect of the invention; (b) formulating said
silicoaluminophosphate molecular sieve, along with a binder and
optionally a matrix material, into a silicoaluminophosphate
molecular sieve catalyst composition comprising from at least 10%
to about 50% molecular sieve; (c) contacting said catalyst
composition with a hydrocarbon feed under conditions sufficient to
convert said hydrocarbon feed into a product comprising
predominantly one or more olefins; (d) polymerizing at least one of
the one or more olefins, optionally with one or more other
comonomers and optionally in the presence of a polymerization
catalyst, under conditions sufficient to form an olefin-based
(co)polymer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 shows an X-ray diffraction (XRD) analysis of a
molecular sieve made according to Comparative Example A1.
[0019] FIG. 2 shows an SEM micrograph of a molecular sieve made
according to Comparative Example A1.
[0020] FIG. 3 shows an XRD analysis of a molecular sieve made
according to Comparative Example A2.
[0021] FIG. 4 shows an SEM micrograph of a molecular sieve made
according to Comparative Example A2.
[0022] FIG. 5 shows an XRD analysis of a molecular sieve made
according to Example 1.
[0023] FIG. 6 shows an SEM micrograph of a molecular sieve made
according to Example 1.
[0024] FIG. 7 shows an XRD analysis of a molecular sieve made
according to Example 2.
[0025] FIG. 8 shows an SEM micrograph of a molecular sieve made
according to Example 2.
[0026] FIG. 9 shows an SEM micrograph of a molecular sieve made
according to Example 3.
[0027] FIG. 10 shows an SEM micrograph of a molecular sieve made
according to Example 4.
[0028] FIG. 11 shows an SEM micrograph of a molecular sieve made
according to Comparative Example B 1.
[0029] FIG. 12 shows an SEM micrograph of a molecular sieve made
according to Example 5.
[0030] FIG. 13 shows an SEM micrograph of a molecular sieve made
according to Example 6.
[0031] FIG. 14 shows an SEM micrograph of a molecular sieve made
according to Example 14.
[0032] FIG. 15 shows a graph of the yield of products made
according to the invention with different silica sources and having
various Si/Al.sub.2 ratios in the synthesis mixture.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0033] Described herein is a method of synthesizing a crystalline
aluminophosphate or silicoaluminophosphate containing a molecular
sieve having 90% or greater CHA framework-type character and to the
use of the resultant molecular sieve as a catalyst in organic
conversion reactions, especially the conversion of oxygenates to
light olefins.
[0034] In particular, it has been found that, by employing a
particular order of addition of components (i.e., phosphorus and
aluminum sources being combined first) and by incorporating certain
organic sources (e.g., organosilicate and optionally also
organophosphate) in the molecular sieve synthesis, it is possible
to produce a 90% or greater CHA framework-type containing molecular
sieve having a desirably reduced crystal size, e.g., 5 microns or
less, instead of over 10 microns.
[0035] In a preferred embodiment, the order of addition of the
components in the mixture (i.e., in step (a)) can be important and
can advantageously be tailored, e.g., to provide better
homogeneity. For instance, step (a) can preferably comprise: (i)
combining the source of phosphorus and the source of aluminum,
optionally with a liquid mixture medium, to form a primary mixture;
(ii) aging the primary mixture for an aging time and under aging
conditions (e.g., at an aging temperature), preferably sufficient
to allow homogenization of the primary mixture, physico-chemical
interaction between the source of phosphorus and the source of
aluminum, or both; and (iii) adding the source of silicon, the at
least one organic template, and optionally additional liquid
mixture medium, to the aged primary mixture to form the synthesis
mixture. In certain cases of this embodiment, within step (iii),
said source of silicon is combined with said primary mixture prior
to adding said at least one organic template (structure directing
agent, or SDA). Advantageously, said primary mixture and said
source of silicon can be combined to form a secondary mixture for a
time and under conditions (e.g., temperature), preferably
sufficient to allow homogenization of the secondary mixture,
physico-chemical interaction between said source of silicon and
said primary mixture, or both, after which said at least one
organic template is combined therewith.
[0036] When a component is added to a mixture to allow
homogenization and/or physico-chemical interaction, the aging time
and temperature are two of the primary conditions. Although a
variety of conditions can exist to allow sufficient contact for
homogenization and/or interaction, in one embodiment, when the
aging temperature is somewhere between 0.degree. C. and 50.degree.
C., the aging time can advantageously be at least 5 minutes, for
example at least 10 minutes, at least 15 minutes, at least 20
minutes, at least 25 minutes, at least 30 minutes, at least 45
minutes, at least 1 hour, or at least 2 hours. Again, when the
aging temperature is somewhere between 0.degree. C. and 50.degree.
C., the aging time does not really have a maximum, but can be up to
350 hours, for example up to 300 hours, up to 250 hours, up to 200
hours, up to 168 hours, up to 96 hours, up to 48 hours, up to 24
hours, up to 16 hours, up to 12 hours, up to 8 hours, up to 6
hours, or up to 4 hours, depending on practical concerns relating
to synthesis timing, cost efficiency, manufacture schedules, or the
like.
[0037] In the present method, a reaction mixture is prepared
comprising a source of aluminum, a source of phosphorous, at least
one organic directing agent, and, optionally, a source of silicon.
Any organic directing agent capable of directing the synthesis of
CHA framework type molecular sieves can be employed, but generally
the directing agent is a compound having the formula (I):
R.sup.1R.sup.2N--R.sup.3 (I)
wherein R.sup.1 and R.sup.2 are independently selected from the
group consisting of alkyl groups having from 1 to 3 carbon atoms
and hydroxyalkyl groups having from 1 to 3 carbon atoms and R.sup.3
is selected from the group consisting of 4- to 8-membered
cycloalkyl groups, optionally substituted by 1 to 3 alkyl groups
having from 1 to 3 carbon atoms; and 4- to 8-membered heterocyclic
groups having from 1 to 3 heteroatoms, said heterocyclic groups
being optionally substituted by 1 to 3 alkyl groups having from 1
to 3 carbon atoms and the heteroatoms in said heterocyclic groups
being selected from the group consisting of O, N, and S.
[0038] More particularly, the organic directing agent is a compound
having the formula (II):
(CH.sub.3).sub.2N--R.sup.3 (II)
wherein R.sup.3 is a 4- to 8-membered cycloalkyl group, especially
a cyclohexyl group, optionally substituted by 1 to 3 methyl groups.
Particular examples of suitable organic directing agents include,
but are not limited to, at least one of
N,N-dimethyl-cyclohexylamine, N,N-dimethyl-methylcyclohexylamine,
N,N-dimethyl-cyclopentylamine, N,N-dimethyl-methylcyclopentylamine,
N,N-dimethyl-cycloheptylamine, and
N,N-dimethyl-methylcycloheptylamine, especially
N,N-dimethyl-cyclohexylamine
[0039] The sources of aluminum, phosphorus, and silicon suitable
for use in the present synthesis method are typically those known
in the art or as described in the literature for the production of
aluminophosphates and silicoaluminophosphates. For example, the
aluminum source may be an aluminum oxide (alumina), optionally
hydrated, an aluminum salt, especially a phosphate, an aluminate,
or a mixture thereof Other sources may include alumina sols or
organic alumina sources, e.g., aluminum alkoxides such as aluminum
isopropoxide. A preferred source is a hydrated alumina, most
preferably pseudoboehmite, which contains about 75% Al.sub.2O.sub.3
and 25% H.sub.2O by weight. Typically, the source of phosphorus is
a phosphoric acid, especially orthophosphoric acid, although other
phosphorus sources, for example, organophosphates (e.g.,
trialkylphosphates such as triethylphosphate) and aluminophosphates
may be used. When organophosphates and/or aluminophosphates are
used, typically they are present collectively in a minor amount
(i.e., less than 50% by weight of the phosphorus source) in
combination with a majority (i.e., at least 50% by weight of the
phosphorus source) of an inorganic phosphorus source (such as
phosphoric acid). Suitable sources of silicon include silica, for
example colloidal silica and fumed silica, as well as organic
silicon source, e.g., a tetraalkyl orthosilicate, preferably such
as tetraethylorthosilicate (TEOS), tetramethylorthosilicate (TMOS),
or the like, or a combination thereof.
[0040] Although, in most embodiments, the sources of silicon,
phosphorus, and aluminum are the only components that form the
framework of a calcined silicoaluminophosphate molecular sieve
according to the invention, it is possible for some small portion
(e.g., typically no more than about 10 wt %, preferably no more
than about 5 wt %) of the silicon source can be substituted with a
source of one or more of magnesium, zinc, iron, cobalt, nickel,
manganese, and chromium.
[0041] In some embodiments, the reaction mixture can have a molar
composition within the following ranges: [0042]
P.sub.2O.sub.5:Al.sub.2O.sub.3 from about 0.75 to about 1.25,
[0043] SiO.sub.2:Al.sub.2O.sub.3 from about 0.01 to about 0.32,
[0044] H.sub.2O:Al.sub.2O.sub.3 from about 25 to about 50, and
[0045] SDA:Al.sub.2O.sub.3 from about 1 to about 3, where SDA
designates the structure directing agent (template), and wherein
the molar ratios for the aluminum, phosphorus, and silicon sources
are calculated based on the oxide forms, regardless of the form of
the source added to the reaction mixture (e.g., whether the
phosphorus source is added to the reaction mixture as phosphoric
acid, H.sub.3PO.sub.4, or as triethylphosphate, the molar ratio is
normalized to P.sub.2O.sub.5 molar equivalents).
[0046] Although the reaction mixture may also contain a source of
fluoride ions, it is found that the present synthesis will proceed
in the absence of fluoride ions, and hence it is generally
preferred to employ a reaction mixture which is substantially free
of fluoride ions.
[0047] Typically, the reaction mixture also contains seeds to
facilitate the crystallization process. The amount of seeds
employed can vary widely, but generally the reaction mixture
comprises from about 0.01 ppm by weight to about 10,000 ppm by
weight, such as from about 100 ppm by weight to about 5,000 by
weight, of said seeds. Generally, the seeds can be homostructural
with the desired product, that is are of a CHA framework type
material, although heterostructural seeds of, for example, an AEI,
LEV, ERI, AFX, or OFF framework-type molecular sieve, or a
combination or intergrowth thereof, may be used. The seeds may be
added to the reaction mixture as a suspension in a liquid medium,
such as water; in some cases, particularly where the seeds are of
relatively small size, the suspension can be colloidal. The
production of colloidal seed suspensions and their use in the
synthesis of molecular sieves are disclosed in, for example,
International Publication Nos. WO 00/06493 and WO 00/06494, both
published on Feb. 10, 2000 and both of which are incorporated
herein by reference.
[0048] Crystallization of the reaction mixture is carried out at
either static or stirred conditions in a suitable reactor vessel,
such as for example, polypropylene jars or Teflon-lined or
stainless steel autoclaves. In one embodiment, the crystallization
regime can involve heating the reaction mixture relatively quickly,
at a rate of more than 10.degree. C./hour, conveniently at least
15.degree. C./hour or at least 20.degree. C./hour, for example from
about 15.degree. C./hour to about 150.degree. C./hour or from about
20.degree. C./hour to about 100.degree. C./hour, to the desired
crystallization temperature, typically between about 50.degree. C.
and about 250.degree. C., for example from about 150.degree. C. to
about 225.degree. C. or from about 150.degree. C. to about
200.degree. C., such as from about 160.degree. C. to about
195.degree. C. In some embodiments, however, the desired
crystallization temperature is additionally at least 165.degree.
C., for example at least 170.degree. C., and can optionally also be
not more than 190.degree. C., for example not more than 185.degree.
C. or not more than 180.degree. C. In any of these embodiments,
when the desired crystallization temperature is reached, the
crystallization can be terminated immediately or from about 5
minutes to about 350 hours, and the reaction mixture can be allowed
to cool; additionally or alternately, the crystallization can run
for at least about 12 hours, preferably at least about 16 hours,
for example at least 24 hours, at least 36 hours, at least 48
hours, at least 60 hours, at least 72 hours, at least 84 hours, at
least 96 hours, at least 120 hours, or at least 144 hours before
cooling. Additionally in this embodiment, on cooling, the
crystalline product can be recovered by standard means, such as by
centrifugation or filtration, then washed and dried.
[0049] In an alternate embodiment, the crystallization regime can
involve heating the reaction mixture slowly, at a rate of less than
8.degree. C./hour, conveniently at least 1.degree. C./hour, such as
from about 2.degree. C./hour to about 6.degree. C./hour, to the
desired crystallization temperature, typically between about
50.degree. C. and about 250.degree. C., for example from about
150.degree. C. to about 225.degree. C. or from about 150.degree. C.
to about 200.degree. C., such as from about 160.degree. C. to about
195.degree. C. In some embodiments, however, the desired
crystallization temperature is additionally at least 165.degree.
C., for example at least 170.degree. C., and can optionally also be
not more than 190.degree. C., for example not more than 185.degree.
C. or not more than 180.degree. C. In any of these embodiments,
when the desired crystallization temperature is reached, the
crystallization can be terminated immediately or at least within
less than 10 hours, such as less than 5 hours, and the reaction
mixture can be allowed to cool. Additionally in this embodiment, on
cooling, the crystalline product can be recovered by standard
means, such as by centrifugation or filtration, then washed and
dried.
[0050] Optionally, the step of inducing crystallization can be done
while stirring.
[0051] In one embodiment, the crystallized silicoaluminophosphate
molecular sieve has a crystal size distribution such that its
average crystal size is no more than 5 .mu.m, preferably no more
than 3.0 .mu.m, for example no more than 2.0 .mu.m, no more than
1.5 .mu.m, no more than 1.2 .mu.m, no more than 1.1 .mu.m, no more
than 1.0 .mu.m, or no more than 0.9 .mu.m.
[0052] As used herein, the term "average crystal size," in
reference to a crystal size distribution, should be understood to
refer to a measurement on a representative sample or an average of
multiple samples that together form a representative sample.
Average crystal size can be measured by SEM, in which case the
crystal size of at least 30 crystals must be measured in order to
obtain an average crystal size, and/or average crystal size can be
measured by a laser light scattering particle size analyzer
instrument, in which case the measured d.sub.50 of the sample(s)
can represent the average crystal size. It should also be
understood that, while many of the crystals dealt with herein are
relatively uniform (for instance, very close to cubic, thus having
little difference between diameter measured along length, height,
or width, e.g., when viewed in an SEM), the "average crystal size,"
when measured visually by SEM, represents the longest distance
along one of the three-dimensional orthogonal axes (e.g., longest
of length, width/diameter, and height, but not diagonal, in a cube,
rectangle, parallelogram, ellipse, cylinder, frusto-cone, platelet,
spheroid, or rhombus, or the like). However, the d.sub.50, when
measured by light scattering in a particle size analyzer, is
reported as a spherical equivalent diameter, regardless of the
shape and/or relative uniformity of shape of the crystals in each
sample. In certain circumstances, the d.sub.50 values measured by
the particle size analyzer may not correspond, even roughly, to the
average crystal size measured visually by a representative SEM
micrograph. Often in these cases, the discrepancy relates to an
agglomeration of relatively small crystals that the particle size
analyzer interprets as a single particle. In such circumstances,
where the d.sub.50 values from the particle size analyzer and the
average crystal size from a representative SEM are significantly
different, the representative SEM micrograph should be the more
accurate measure of "average crystal size."
[0053] Preferably, the Si/Al.sub.2 ratio added to the synthesis
mixture can be as close as possible to the Si/Al.sub.2 ratio of the
crystallized silicoaluminophosphate molecular sieve (e.g.,
difference between the Si/Al.sub.2 ratio in the synthesis mixture
and in the crystallized silicoaluminophosphate molecular sieve can
be no more than 0.10, preferably no more than 0.08, for example no
more than 0.07) and/or the synthesis mixture and the crystallized
silicoaluminophosphate molecular sieve can both exhibit a
relatively low Si/Al.sub.2 ratio (e.g., both can be less than 0.33,
preferably less than 0.30, for example no more than 0.25, no more
than 0.20, no more than 0.15, or no more than 0.10).
[0054] In a preferred embodiment, one or more of the following are
satisfied: the source of aluminum comprises alumina; the source of
phosphorus comprises phosphoric acid and an organophosphate
comprising a trialkylphosphate; the source of silicon can include
an organosilicate comprising a tetraalkylorthosilicate; and the at
least one organic template comprises
N,N-dimethylcyclohexylamine.
[0055] The product of the crystallization is an aluminophosphate or
silicoaluminophosphate containing a CHA framework-type molecular
sieve having an X-ray diffraction pattern including at least the
d-spacings shown in Table 1 below:
TABLE-US-00001 TABLE 1 Relative Intensities d(A) I/Io (%) 9.26 100
6.30 20 5.64 15 5.51 57 4.96 25 4.92 27 4.29 76 4.18 21 3.55 32
3.50 20 3.42 10 2.91 22 2.88 26 2.87 19
[0056] Although the crystallization product is normally a single
phase CHA framework-type molecular sieve, in some cases the product
may contain an intergrowth of a CHA framework-type molecular sieve
with, for example an AEI framework-type molecular sieve or small
amounts of other crystalline phases, such as APC and/or AFI
framework-type molecular sieves. In one embodiment, it is
preferable for the crystallization product to have as high an
amount of CHA framework type as possible, e.g., at least 95% CHA
framework-type character, or even about 100% CHA framework-type
character (or as close as possible to single phase CHA
framework-type character as can currently be measured). Without
being bound by theory, it is believed that silicoaluminophosphate
molecular sieves having increased CHA framework-type character
(and/or increased uniformity of distribution of silicon within the
molecular sieve framework structure, i.e., decreased amounts of
silicon islanding) can advantageously exhibit better performance
(e.g., increased POS, which means prime olefin selectivity, or
selectivity to the combination of ethylene and propylene, and
optionally also POR, which means prime olefin, or
ethylene-to-propylene, ratio) in oxygenates-to-olefins conversion
reactions, particularly in methanol-to-olefins conversion
reactions.
[0057] As a result of the crystallization process, the recovered
crystalline product contains within its pores at least a portion of
the organic directing agent used in the synthesis. In a preferred
embodiment, activation is performed in such a manner that the
organic directing agent is removed from the molecular sieve,
leaving active catalytic sites within the microporous channels of
the molecular sieve open for contact with a feedstock. The
activation process is typically accomplished by calcining, or
essentially heating the molecular sieve comprising the template at
a temperature of from about 200.degree. C. to about 800.degree. C.
in the presence of an oxygen-containing gas. In some cases, it may
be desirable to heat the molecular sieve in an environment having a
low or zero oxygen concentration. This type of process can be used
for partial or complete removal of the organic directing agent from
the intracrystalline pore system.
[0058] Once the crystalline product has been activated, it can be
formulated into a catalyst composition by combination with other
materials, such as binders and/or matrix materials, which provide
additional hardness or catalytic activity to the finished
catalyst.
[0059] Materials which can be blended with the present molecular
sieve material include a large variety of inert and catalytically
active materials. These materials include compositions such as
kaolin and other clays, various forms of rare earth metals, other
non-zeolite catalyst components, zeolite catalyst components,
alumina or alumina sol, titania, zirconia, quartz, silica or silica
sol, and mixtures thereof. These components are also effective in
reducing overall catalyst cost, acting as a thermal sink to assist
in heat shielding the catalyst during regeneration, densifying the
catalyst and increasing catalyst strength. When blended with such
components, the amount of present CHA-containing crystalline
material contained in the final catalyst product ranges from 10 to
90 weight percent of the total catalyst, preferably 20 to 80 weight
percent of the total catalyst.
[0060] The CHA framework type crystalline material produced by the
present process can be used to dry gases and liquids; for selective
molecular separation based on size and polar properties; as an
ion-exchanger; as a chemical carrier; in gas chromatography; and as
a catalyst in organic conversion reactions. Examples of suitable
catalytic uses of the CHA framework type crystalline material
described herein include (a) hydrocracking of heavy petroleum
residual feedstocks, cyclic stocks and other hydrocrackate charge
stocks, normally in the presence of a hydrogenation component
selected from Groups 6 and 8-10 of the Periodic Table of Elements;
(b) dewaxing, including isomerization dewaxing, to selectively
remove straight chain paraffins from hydrocarbon feedstocks
typically boiling above 177.degree. C., including raffinates and
lubricating oil basestocks; (c) catalytic cracking of hydrocarbon
feedstocks, such as naphthas, gas oils, and residual oils, normally
in the presence of a large pore cracking catalyst, such as zeolite
Y; (d) oligomerization of straight and branched chain olefins
having from 2-21, preferably 2-5, carbon atoms, to produce medium
to heavy olefins which are useful for both fuels, e.g., gasoline or
a gasoline blending stock, and chemicals; (e) isomerization of
olefins, particularly olefins having 4-6 carbon atoms, and
especially normal butene to produce iso-olefins; (f) upgrading of
lower alkanes, such as methane, to higher hydrocarbons, such as
ethylene and benzene; (g) disproportionation of alkylaromatic
hydrocarbons, such as toluene, to produce dialkylaromatic
hydrocarbons, such as xylenes; (h) alkylation of aromatic
hydrocarbons, such as benzene, with olefins, such as ethylene and
propylene, to produce alkylated aromatics, such as ethylbenzene and
cumene; (i) isomerization of dialkylaromatic hydrocarbons, such as
xylenes; (j) catalytic reduction of nitrogen oxides; and (k)
synthesis of monoalkylamines and dialkylamines.
[0061] In particular, the CHA framework type crystalline material
produced by the present process is useful as a catalyst in the
conversion of oxygenates to one or more olefins, particularly
ethylene and propylene. As used herein, the term "oxygenates" is
defined to include, but is not necessarily limited to, aliphatic
alcohols, ethers, carbonyl compounds (aldehydes, ketones,
carboxylic acids, carbonates, and the like), and also compounds
containing hetero-atoms, such as, halides, mercaptans, sulfides,
amines, and mixtures thereof The aliphatic moiety will normally
contain from 1-10 carbon atoms, such as from 1-4 carbon atoms.
[0062] Representative oxygenates include lower straight chain or
branched aliphatic alcohols, their unsaturated counterparts, and
their nitrogen, halogen, and sulfur analogues. Examples of suitable
oxygenate compounds can include, but are not necessarily limited
to: methanol; ethanol; n-propanol; isopropanol; C.sub.4 to C.sub.10
alcohols; methyl ethyl ether; dimethyl ether; diethyl ether;
di-isopropyl ether; methyl mercaptan; methyl sulfide; methyl amine;
ethyl mercaptan; di-ethyl sulfide; di-ethyl amine; ethyl chloride;
formaldehyde; di-methyl carbonate; di-methyl ketone; acetic acid;
n-alkyl amines; n-alkyl halides; n-alkyl sulfides having n-alkyl
groups comprising from 3-10 carbon atoms; and the like; and
mixtures thereof Particularly suitable oxygenate compounds are
methanol, dimethyl ether, and mixtures thereof, and most preferably
comprise methanol. As used herein, the term "oxygenate" designates
only the organic material used as the feed. The total charge of
feed to the reaction zone may contain additional compounds, such as
diluents.
[0063] In one embodiment of the oxygenate conversion process, a
feedstock comprising an organic oxygenate, optionally with one or
more diluents, is contacted in the vapor phase in a reaction zone
with a catalyst comprising the present molecular sieve at effective
process conditions so as to produce the desired olefins.
Alternatively, the process may be carried out in a liquid or a
mixed vapor/liquid phase. When the process is carried out in the
liquid phase or a mixed vapor/liquid phase, different conversion
rates and selectivities of feedstock-to-product may result
depending upon the catalyst and the reaction conditions.
[0064] When present, the diluent(s) is(are) generally non-reactive
to the feedstock or molecular sieve catalyst composition and is
typically used to reduce the concentration of the oxygenate in the
feedstock. Non-limiting examples of suitable diluents include
helium, argon, nitrogen, carbon monoxide, carbon dioxide, water,
essentially non-reactive paraffins (especially alkanes such as
methane, ethane, and propane), essentially non-reactive aromatic
compounds, and mixtures thereof The most preferred diluents include
water and nitrogen, with water being particularly preferred.
Diluent(s) may comprise from about 1 mol % to about 99 mol % of the
total feed mixture.
[0065] The temperature employed in the oxygenate conversion process
may vary over a wide range, such as from about 200.degree. C. to
about 1000.degree. C., for example from about 250.degree. C. to
about 800.degree. C., including from about 250.degree. C. to about
750.degree. C., conveniently from about 300.degree. C. to about
650.degree. C., typically from about 350.degree. C. to about
600.degree. C. and particularly from about 400.degree. C. to about
600.degree. C.
[0066] Light olefin products will form, although not necessarily in
optimum amounts, at a wide range of pressures, including but not
limited to autogenous pressures and pressures in the range from
about 0.1 kPa to about 10 MPa. Conveniently, the pressure can be in
the range from about 7 kPa to about 5 MPa, such as from about 50
kPa to about 1 MPa. The foregoing pressures are exclusive of
diluents, if any are present, and refer to the partial pressure of
the feedstock as it relates to oxygenate compounds and/or mixtures
thereof Lower and upper extremes of pressure may adversely affect
selectivity, conversion, coking rate, and/or reaction rate;
however, light olefins such as ethylene and/or propylene still may
form.
[0067] In a preferred embodiment, the method of converting
hydrocarbons into olefins according to the invention comprises: (a)
preparing a silicoaluminophosphate molecular sieve according to the
methods disclosed hereinabove; (b) formulating said
silicoaluminophosphate molecular sieve, along with a binder and
optionally a matrix material, into a silicoaluminophosphate
molecular sieve catalyst composition, typically comprising from at
least 10% to about 50% molecular sieve; and (c) contacting said
catalyst composition with a hydrocarbon feed under conditions
sufficient to convert said hydrocarbon feed into a product
comprising predominantly one or more olefins, preferably to attain
a prime olefin selectivity of at least 70 wt % (as measured at
about 500.degree. C.). Preferably, the hydrocarbon feed is an
oxygenate-containing feed comprising methanol, dimethylether, or a
combination thereof, and the one or more olefins typically
comprises ethylene, propylene, or a combination thereof.
[0068] A wide range of weight hourly space velocities (WHSV) for
the feedstock will function in the oxygenate conversion process.
WHSV is defined as weight of feed (excluding diluents) per hour per
weight of a total reaction volume of molecular sieve catalyst
(excluding inert and/or fillers). The WHSV generally should be in
the range from about 0.01 hr.sup.-1 to about 500 hr.sup.-1, such
from about 0.5 hr.sup.-1 to about 300 hr.sup.-1, for example from
about 0.1 hr.sup.-1 to about 200 hr.sup.-1.
[0069] A practical embodiment of a reactor system for the oxygenate
conversion process is a circulating fluid bed reactor with
continuous regeneration. Fixed beds are generally not preferred for
the process, because oxygenate-to-olefin conversion is a highly
exothermic process that requires several stages with intercoolers
or other cooling devices. The reaction also results in a high
pressure drop, due to the production of low pressure, low density
gas.
[0070] Because the catalyst typically needs to be regenerated
frequently, the reactor should preferably allow easy removal of at
least a portion of the catalyst to a regenerator, where the
catalyst can be subjected to a regeneration medium, such as a gas
comprising oxygen, for example air, to burn off coke from the
catalyst, which should restore at least some of the catalyst
activity. The conditions of temperature, oxygen partial pressure,
and residence time in the regenerator can typically be selected to
achieve a coke content on regenerated catalyst of less than about 1
wt %, for example less than about 0.5 wt %. At least a portion of
the regenerated catalyst should be returned to the reactor.
[0071] In a preferred embodiment, the method of forming an
olefin-based polymer product comprises: (a) preparing a
silicoaluminophosphate molecular sieve according to the methods
described hereinabove; (b) formulating said silicoaluminophosphate
molecular sieve, along with a binder and optionally a matrix
material, into a silicoaluminophosphate molecular sieve catalyst
composition comprising from at least 10% to about 50% molecular
sieve; (c) contacting said catalyst composition with a hydrocarbon
feed under conditions sufficient to convert said hydrocarbon feed
into a product comprising predominantly one or more olefins,
preferably to attain a prime olefin selectivity of at least 70 wt %
(as measured at about 500.degree. C.); and (d) polymerizing at
least one of the one or more olefins, optionally with one or more
other comonomers and optionally (but preferably) in the presence of
a polymerization catalyst, under conditions sufficient to form an
olefin-based (co)polymer. Preferably, in this preferred embodiment,
the hydrocarbon feed is an oxygenate-containing feed comprising
methanol, dimethylether, or a combination thereof, the one or more
olefins typically comprises ethylene, propylene, or a combination
thereof, and the olefin-based (co)polymer is an ethylene-containing
(co)polymer, a propylene-containing (co)polymer, or a copolymer,
mixture, or blend thereof.
[0072] Additionally or alternately, the invention can be described
by the following embodiments.
[0073] Embodiment 1. A method of preparing a silicoaluminophosphate
molecular sieve having a desired crystal size, the method
comprising: (a) combining a source of phosphorus and a source of
aluminum, optionally with a liquid mixture medium, to form a
primary mixture; (b) aging the primary mixture for an aging time
and under aging conditions sufficient to allow homogenization of
the primary mixture, physico-chemical interaction between the
source of phosphorus and the source of aluminum, or both; (c)
adding a source of silicon, at least one organic template, and
optionally additional liquid mixture medium, to the aged primary
mixture to form a synthesis mixture; and (d) inducing
crystallization of a silicoaluminophosphate molecular sieve, which
exhibits 90% or greater CHA framework type character, from said
synthesis mixture at a crystallization temperature, wherein said
source of silicon comprises an organosilicate and said source of
phosphorus optionally comprises an organophosphate, and wherein the
crystallized silicoaluminophosphate molecular sieve has a crystal
size distribution such that the average crystal size is not greater
than 5 .mu.m.
[0074] Embodiment 2. The method of embodiment 1, wherein the at
least one organic template contains (i) a 4- to 8-membered
cycloalkyl group, optionally substituted by 1-3 alkyl groups having
from 1-3 carbon atoms, or (ii) a 4- to 8-membered heterocyclic
group having from 1-3 heteroatoms, said heterocyclic group being
optionally substituted by 1-3 alkyl groups having from 1-3 carbon
atoms, and said heteroatoms in said heterocyclic groups being
selected from the group consisting of O, N, and S.
[0075] Embodiment 3. The method of embodiment 1 or embodiment 2,
wherein the at least one organic template comprises
N,N-dimethylcyclohexylamine
[0076] Embodiment 4. The method of any of the previous embodiments,
wherein the crystallized silicoaluminophosphate molecular sieve
exhibits a Si/Al.sub.2 ratio not more than 0.10 greater than the
Si/Al.sub.2 ratio of the synthesis mixture.
[0077] Embodiment 5. The method of any of the previous embodiments,
wherein said crystallization temperature is between 150.degree. C.
and 200.degree. C.
[0078] Embodiment 6. The method of any of the previous embodiments,
wherein the crystallized silicoaluminophosphate molecular sieve has
a crystal size distribution such that the average crystal size is
less than 2.0 .mu.m.
[0079] Embodiment 7. The method of any of the previous embodiments,
wherein the crystallized silicoaluminophosphate molecular sieve has
a crystal size distribution such that the average crystal size is
less than 1.2 .mu.m.
[0080] Embodiment 8. The method of any of the previous embodiments,
wherein the inducing step is done while stirring.
[0081] Embodiment 9. The method of any of the previous embodiments,
wherein, within step (c), said source of silicon is combined with
said primary mixture prior to adding said at least one organic
template.
[0082] Embodiment 10. The method of embodiment 9, wherein said
primary mixture and said source of silicon are combined to form a
secondary mixture for a time and under conditions sufficient to
allow homogenization of the secondary mixture, physico-chemical
interaction between said source of silicon and said primary
mixture, or both, after which said at least one organic template is
combined therewith.
[0083] Embodiment 11. The method of any of the previous
embodiments, wherein the synthesis mixture and the crystallized
silicoaluminophosphate molecular sieve both exhibit a Si/Al.sub.2
ratio less than 0.33.
[0084] Embodiment 12. The method of any of embodiments 1-2 and
4-11, wherein one or more of the following are satisfied: the
source of aluminum comprises alumina; the source of phosphorus
comprises phosphoric acid and an organophosphate comprising a
trialkylphosphate; the organosilicate comprises a
tetraalkylorthosilicate; and the at least one organic template
comprises N,N-dimethylcyclohexylamine
[0085] Embodiment 13. The method of any of the previous
embodiments, wherein the organosilicate comprises
tetramethylorthosilicate, tetraethylorthosilicate, or a combination
thereof.
[0086] Embodiment 14. The method of any of the previous
embodiments, wherein step (b) was accomplished using seeds having a
framework type of CHA, AEI, AFX, LEV, an intergrowth thereof, or a
combination thereof.
[0087] Embodiment 15. A method of converting hydrocarbons into
olefins comprising: (a) preparing a silicoaluminophosphate
molecular sieve according to the method of any of the previous
embodiments; (b) formulating said silicoaluminophosphate molecular
sieve, along with a binder and optionally a matrix material, into a
silicoaluminophosphate molecular sieve catalyst composition
comprising from at least 10% to about 50% molecular sieve; and (c)
contacting said catalyst composition with a hydrocarbon feed under
conditions sufficient to convert said hydrocarbon feed into a
product comprising predominantly one or more olefins.
[0088] Embodiment 16. The method of embodiment 15, wherein the
hydrocarbon feed is an oxygenate-containing feed comprising
methanol, dimethylether, or a combination thereof, and wherein the
one or more olefins comprises ethylene, propylene, or a combination
thereof.
[0089] Embodiment 17. A method of forming an olefin-based polymer
product comprising: (a) preparing a silicoaluminophosphate
molecular sieve according to the method of any of embodiments 1-14;
(b) formulating said silicoaluminophosphate molecular sieve, along
with a binder and optionally a matrix material, into a
silicoaluminophosphate molecular sieve catalyst composition
comprising from at least 10% to about 50% molecular sieve; (c)
contacting said catalyst composition with a hydrocarbon feed under
conditions sufficient to convert said hydrocarbon feed into a
product comprising predominantly one or more olefins; (d)
polymerizing at least one of the one or more olefins, optionally
with one or more other comonomers and optionally in the presence of
a polymerization catalyst, under conditions sufficient to form an
olefin-based (co)polymer.
[0090] Embodiment 18. The method of embodiment 17, wherein the
hydrocarbon feed is an oxygenate-containing feed comprising
methanol, dimethylether, or a combination thereof, wherein the one
or more olefins comprises ethylene, propylene, or a combination
thereof, and wherein the olefin-based (co)polymer is an
ethylene-containing (co)polymer, a propylene-containing
(co)polymer, or a copolymer, mixture, or blend thereof
[0091] The invention will now be more particularly described with
reference to the following Examples and the accompanying
drawings.
EXAMPLES
[0092] The analysis techniques described below were among those
used in characterizing various samples from the Examples.
ICP-OES
[0093] Elemental analysis has been done using ICP-OES (Inductively
Coupled Plasma-Optical Emission Spectrometry). Samples were
dissolved in a mixture of acids and diluted in deionized water. The
instrument (Simultaneous VISTA-MPX from Varian) was calibrated
using commercial available standards (typically at least 3
standards and a blank). The power used was about 1.2 kW, plasma
flow about 13.5 L/min, and nebulizer pressure about 200 kPa for all
lines. Results are expressed in wt % or ppm by weight (wppm), and
the values are recalculated to Si/Al.sub.2 molar ratios.
XRD
[0094] Either of two X-ray diffractometers was used: a STOE Stadi-P
Combi
[0095] Transmission XRD and a Scintag X2 Reflection XRD with
optional sample rotation. Cu-K.sub..alpha. radiation was used.
Typically, a step size of 0.2.degree. 2.THETA. and a measurement
time of about 1 hour were used.
SEM
[0096] A JEOL JSM-6340F Field-Emission-Gun scanning electron
microscope (SEM) was used, operating at about 2 kV and about 12
.mu.A. Prior to measurement, samples were dispersed in ethanol,
subjected to ultrasonic treatment for about 5 to about 30 minutes,
deposited on SEM sample holders, and dried at room temperature and
pressure (about 20-25.degree. C. and about 101 kPa). If an average
particle size was determined based on the SEM micrographs,
typically the measurement was performed on at least 30 crystals. In
case of the near cubic crystals, the average was based on the sizes
of one of the edges of each crystal.
PSA
[0097] Particle size analysis was performed using a Mastersizer
APA2000 from Malvern Instruments Limited, equipped with a 4 mW
laser beam, based on laser scattering by randomly moving particles
in a liquid medium. The samples to be measured were dispersed in
water under continuous ultrasonic treatment to ensure proper
dispersion. The pump speed applied was 2000 RPM, and the stirrer
speed was 800 RPM. The parameters used in the operation procedure
were: Refractive Index=1.544, Absorption=0.1. The results were
calculated using the "general purpose-enhanced sensitivity" model.
The results were expressed as d.sub.50, meaning that 50 vol % of
the particles were smaller than the value. The average of at least
2 measurements, with a delay of at least about 10 seconds, was
reported.
Comparative Example A1
[0098] A synthesis mixture having a molar composition of about 0.15
SiO.sub.2:P.sub.2O.sub.5:Al.sub.2O.sub.3:1.5 DMCHA:40 H.sub.2O, as
well as 100 wt ppm (wppm) seeds, was prepared according to the
following procedure. A solution of phosphoric acid was prepared by
combining phosphoric acid [Acros, 85%] and water. To this solution
was added the appropriate amount of Condea Pural SB [Sasol, 74.2 wt
% Al.sub.2O.sub.3], and the slurry was stirred for about 10 minutes
at about 10.degree. C. To this mixture was added the appropriate
amount of Ludox AS40 [ammonium stabilized silica sol containing 40
wt % SiO.sub.2, from Grace NV] and the slurry was stirred for about
another 10 minutes at about 10.degree. C. Then the appropriate
amount of dimethylcyclohexylamine [DMCHA, 99%, from Purum Fluka]
was added. This mixture was stirred for about 10 minutes before the
seeds (SAPO-34 seeds) were added. The final mixture was transferred
to an autoclave which was stirred at approximately room temperature
(about 20-25.degree. C.) for about 2 hours, followed by heating,
while stirring, to about 170.degree. C. with a heat-up rate of
about 40.degree. C./hr. After about 72 hours this temperature, the
autoclave was cooled to approximately room temperature, and the
solids were washed with demineralized water and dried at about
120.degree. C. The yield was determined by weighing the dried
solids and dividing this weight by the weight of the initial
synthesis mixture. The so-calculated yield was about 12.5 wt %. The
phase purity of the sample was determined by X-ray diffraction to
contain CHA framework, by virtue of exhibiting the peaks listed in
Table 1 above, but also contained a significant amount of peaks
indicating AFI framework. The XRD pattern is shown in FIG. 1. An
SEM micrograph was recorded (FIG. 2), and the crystal size was
approximated to be about 10 .mu.m.
Comparative Example A2
[0099] A synthesis mixture having a molar composition of about 0.15
SiO.sub.2:0.75 P.sub.2O.sub.5:Al.sub.2O.sub.3:1.5 DMCHA:40
H.sub.2O, as well as 100 wt ppm seeds, was prepared according to
the following procedure. A solution of phosphoric acid was prepared
by combining phosphoric acid [Acros, 85%] and water. To this
solution was added the appropriate amount of Condea Pural SB
[Sasol, 74.2 wt % Al.sub.2O.sub.3], and the slurry was stirred for
about 10 minutes at about 10.degree. C. To this mixture was added
the appropriate amount of Ludox AS40 [ammonium stabilized silica
sol containing 40 wt % SiO.sub.2, from Grace NV] and the slurry was
stirred for about another 10 minutes at about 10.degree. C. Then
the appropriate amount of dimethylcyclohexylamine [DMCHA, 99%, from
Purum Fluka] was added. This mixture was stirred for about 10
minutes before the seeds (SAPO-34 seeds) were added. The final
mixture was transferred to an autoclave which was stirred at
approximately room temperature for about 2 hours, followed by
heating, while stirring, to about 170.degree. C. with a heat-up
rate of about 40.degree. C./hr. After about 72 hours this
temperature, the autoclave was cooled to approximately room
temperature, and the solids were washed with demineralized water
and dried at about 120.degree. C. The yield was determined by
weighing the dried solids and dividing this weight by the weight of
the initial synthesis mixture. The so-calculated yield was about
14.9 wt %. The phase purity of the sample was determined by X-ray
diffraction and was characterized substantially by the d-spacings
shown in Table 1 above. The XRD pattern is shown in FIG. 3. An SEM
micrograph was recorded (FIG. 4), and the crystal size was
approximated to be about 10 .mu.m or smaller.
Example 1
[0100] A synthesis mixture having a molar composition of about 0.15
SiO.sub.2:P.sub.2O.sub.5:Al.sub.2O.sub.3:1.5 DMCHA:40 H.sub.2O, as
well as 100 wt ppm seeds, was prepared according to the following
procedure. A solution of phosphoric acid was prepared by combining
phosphoric acid [Acros, 85%] and water. About 25% of this
phosphoric acid solution was removed and in its place a
corresponding molar amount of triethylphosphate [TEP, 99.8+%, from
Aldrich] was added. To this solution was added the appropriate
amount of Condea Pural SB [Sasol, 74.2 wt % Al.sub.2O.sub.3], and
the slurry was stirred for about 10 minutes at about 10.degree. C.
To this mixture was added the appropriate amount of Ludox AS40
[ammonium stabilized silica sol containing 40 wt % SiO.sub.2, from
Grace NV] and the slurry was stirred for about another 10 minutes
at about 10.degree. C. Then the appropriate amount of
dimethylcyclohexylamine [DMCHA, 99%, from Purum Fluka] was added.
This mixture was stirred for about 10 minutes before the seeds
(SAPO-34 seeds) were added. The final mixture was transferred to an
autoclave which was stirred at approximately room temperature for
about 2 hours, followed by heating, while stirring, to about
170.degree. C. with a heat-up rate of about 40.degree. C./hr. After
about 72 hours this temperature, the autoclave was cooled to
approximately room temperature, and the solids were washed with
demineralized water and dried at about 120.degree. C. The yield was
determined by weighing the dried solids and dividing this weight by
the weight of the initial synthesis mixture. The so-calculated
yield was about 15.5 wt %. The phase purity of the sample was
determined by X-ray diffraction and was characterized substantially
by the d-spacings shown in Table 1 above. The XRD pattern is shown
in FIG. 5. An SEM micrograph was recorded (FIG. 6), and the crystal
size was determined to be about 5 .mu.m or smaller.
Example 2
[0101] A synthesis mixture having a molar composition of about 0.15
SiO.sub.2:P.sub.2O.sub.5:Al.sub.2O.sub.3:1.5 DMCHA:35 H.sub.2O, as
well as 100 wt ppm seeds, was prepared according to the following
procedure. A solution of phosphoric acid was prepared by combining
phosphoric acid [Acros, 85%] and water. About 25 mol % of this
phosphoric acid solution was removed. To this solution was added
the appropriate amount of Condea Pural SB [Sasol, 74.2 wt %
Al.sub.2O.sub.3], and the slurry was stirred for about 10 minutes
at about 10.degree. C. To this mixture was added the appropriate
amount of Ludox AS40 [40 wt % SiO.sub.2, from Grace NV] and the
slurry was stirred for about another 10 minutes at about 10.degree.
C. Then the appropriate amount of dimethylcyclohexylamine [DMCHA,
99%, from Purum Fluka] was added. To this mixture was added
triethylphosphate [TEP, 99.8+%, from Aldrich] in a molar amount
corresponding to the removed phosphoric acid. This mixture was
stirred for about 10 minutes before the seeds (SAPO-34 seeds) were
added. The final mixture was transferred to an autoclave which was
stirred at approximately room temperature for about 2 hours,
followed by heating, while stirring, to about 170.degree. C. with a
heat-up rate of about 40.degree. C./hr. After about 72 hours this
temperature, the autoclave was cooled to approximately room
temperature, and the solids were washed with demineralized water
and dried at about 120.degree. C. The yield was determined by
weighing the dried solids and dividing this weight by the weight of
the initial synthesis mixture. The so-calculated yield was about
13.8 wt %. The phase purity of the sample was determined by X-ray
diffraction and was characterized substantially by the d-spacings
shown in Table 1 above. The XRD pattern is shown in FIG. 7. An SEM
micrograph was recorded (FIG. 8), and the crystal size was
determined to be about 5 .mu.m or smaller.
Example 3
[0102] A synthesis mixture having a molar composition of about 0.15
SiO.sub.2:P.sub.2O.sub.5:Al.sub.2O.sub.3:1.5 DMCHA:40 H.sub.2O, as
well as 100 wt ppm seeds, was prepared according to the following
procedure. A solution of phosphoric acid was prepared by combining
phosphoric acid [Acros, 85%] and water. About 25 mol % of this
phosphoric acid solution was removed. To this solution was added
the appropriate amount of Condea Pural SB [Sasol, 74.2 wt %
Al.sub.2O.sub.3], and the slurry was stirred for about 10 minutes
at about 10.degree. C. To this mixture was added the appropriate
amount of tetraethylorthosilicate [TEOS, 98%, from Aldrich] and the
slurry was stirred for about another 10 minutes at about 10.degree.
C. Then the appropriate amount of dimethylcyclohexylamine [DMCHA,
99%, from Purum Fluka] was added. To this mixture was added
triethylphosphate [TEP, 99.8+%, from Aldrich] in a molar amount
corresponding to the removed phosphoric acid. This mixture was
stirred for about 10 minutes before the seeds (SAPO-34 seeds) were
added. The final mixture was transferred to an autoclave which was
stirred at approximately room temperature for about 2 hours,
followed by heating, while stirring, to about 170.degree. C. with a
heat-up rate of about 40.degree. C./hr.
[0103] After about 72 hours this temperature, the autoclave was
cooled to approximately room temperature, and the solids were
washed with demineralized water and dried at about 120.degree. C.
The phase purity of the sample was determined by X-ray diffraction
and was characterized substantially by the d-spacings shown in
Table 1 above. An SEM micrograph was recorded (FIG. 9), and the
crystal size was determined to be smaller than about 1 .mu.m.
Example 4
[0104] A synthesis mixture having a molar composition of about 0.15
SiO.sub.2:P.sub.2O.sub.5:Al.sub.2O.sub.3:1.5 DMCHA:35 H.sub.2O, as
well as 100 wt ppm seeds, was prepared according to the following
procedure. A solution of phosphoric acid was prepared by combining
phosphoric acid [Acros, 85%] and water. About 25 mol % of this
phosphoric acid solution was removed. To this solution was added
the appropriate amount of Condea Pural SB [Sasol, 74.2 wt %
Al.sub.2O.sub.3], and the slurry was stirred for about 10 minutes
at about 10.degree. C. To this mixture was added the appropriate
amount of tetraethylorthosilicate [TEOS, 98%, from Aldrich] and the
slurry was stirred for about another 10 minutes at about 10.degree.
C. Then the appropriate amount of dimethylcyclohexylamine [DMCHA,
99%, from Purum Fluka] was added. To this mixture was added
triethylphosphate [TEP, 99.8+%, from Aldrich] in a molar amount
corresponding to the removed phosphoric acid. This mixture was
stirred for about 10 minutes before the seeds (SAPO-34 seeds) were
added. The final mixture was transferred to an autoclave which was
stirred at approximately room temperature for about 2 hours,
followed by heating, while stirring, to about 170.degree. C. with a
heat-up rate of about 40.degree. C./hr. After about 72 hours this
temperature, the autoclave was cooled to approximately room
temperature, and the solids were washed with demineralized water
and dried at about 120.degree. C. The phase purity of the sample
was determined by X-ray diffraction and was characterized
substantially by the d-spacings shown in Table 1 above. An SEM
micrograph was recorded (FIG. 10), and the crystals appear to be
relatively homogeneous in size and smaller than about 1 .mu.m.
Comparative Example B1
[0105] A synthesis mixture having a molar composition of about 0.15
SiO.sub.2:P.sub.2O.sub.5:Al.sub.2O.sub.3:2 DMCHA:40 H.sub.2O, as
well as 100 wt ppm seeds, was prepared according to the following
procedure. A solution of phosphoric acid was prepared by combining
phosphoric acid [Acros, 85%] and water. To this solution was added
the appropriate amount of Condea Pural SB [Sasol, 75.6 wt %
Al.sub.2O.sub.3], and the slurry was stirred for about 1 hour at
about 10.degree. C. To this mixture was added the appropriate
amount of Ludox AS40 [ammonium stabilized silica sol containing 40
wt % SiO.sub.2, from Grace NV]. Then the appropriate amount of
dimethylcyclohexylamine [DMCHA, 99%, from Purum Fluka] was added.
This mixture was stirred for about 10 minutes before the seeds
(SAPO-34 seeds) were added. The final mixture was transferred to an
autoclave which was heated, while stirring, to about 170.degree. C.
with a heat-up rate of about 20.degree. C./hr. After about 24 hours
this temperature, the autoclave was cooled to approximately room
temperature, and the solids were washed with demineralized water
and dried at about 120.degree. C. The yield was determined by
weighing the dried solids and dividing this weight by the weight of
the initial synthesis mixture. The so-calculated yield was about
17.2 wt %. The phase purity of the sample was determined by X-ray
diffraction and was characterized substantially by the d-spacings
shown in Table 1 above. An SEM micrograph was recorded (FIG. 11),
and the crystal size was determined, on average, to be
approximately 2.5 .mu.m.
Example 5
[0106] A synthesis mixture having a molar composition of about 0.15
SiO.sub.2:P.sub.2O.sub.5:Al.sub.2O.sub.3:2 DMCHA:40 H.sub.2O, as
well as 100 wt ppm seeds, was prepared according to the following
procedure. A solution of phosphoric acid was prepared by combining
phosphoric acid [Acros, 85%] and water. To this solution was added
the appropriate amount of Condea Pural SB [Sasol, 75.6 wt %
Al.sub.2O.sub.3], and the slurry was stirred for about 1 hour at
about 10.degree. C. To this mixture was added the appropriate
amount of tetraethylorthosilicate [TEOS, 98%, from Aldrich]. Then
the appropriate amount of dimethylcyclohexylamine [DMCHA, 99%, from
Purum Fluka] was added. This mixture was stirred for about 10
minutes before the seeds (SAPO-34 seeds) were added. The final
mixture was transferred to an autoclave which was heated, while
stirring, to about 170.degree. C. with a heat-up rate of about
20.degree. C./hr. After about 24 hours this temperature, the
autoclave was cooled to approximately room temperature, and the
solids were washed with demineralized water and dried at about
120.degree. C. The yield was determined by weighing the dried
solids and dividing this weight by the weight of the initial
synthesis mixture. The so-calculated yield was about 10.5 wt %. The
phase purity of the sample was determined by X-ray diffraction and
was characterized substantially by the d-spacings shown in Table 1
above. An SEM micrograph was recorded (FIG. 12), and the crystal
size was determined, on average, to be about 0.4 .mu.m or
smaller.
Example 6
[0107] A synthesis mixture having a molar composition of about 0.11
SiO.sub.2:P.sub.2O.sub.5:Al.sub.2O.sub.3:2 DMCHA:40 H.sub.2O, as
well as 400 wt ppm seeds, was prepared according to the following
procedure. A solution of phosphoric acid was prepared by combining
phosphoric acid [Acros, 85%] and water. To this solution was added
the appropriate amount of Condea Pural SB [Sasol, 75.6 wt %
Al.sub.2O.sub.3], and the slurry was stirred for about 1 hour at
about 10.degree. C. To this mixture was added the appropriate
amount of tetraethylorthosilicate [TEOS, 98%, from Aldrich]. This
mixture was then aged at about 10.degree. C. while stirring for
about another one hour. Then the appropriate amount of
dimethylcyclohexylamine [DMCHA, 99%, from Purum Fluka] was added.
This mixture was stirred for about 10 minutes before the seeds
(SAPO-34 seeds) were added. The final mixture was transferred to an
autoclave which was heated, while stirring, to about 160.degree. C.
with a heat-up rate of about 40.degree. C./hr. After about 144
hours this temperature, the autoclave was cooled to approximately
room temperature, and the solids were washed with demineralized
water and dried at about 120.degree. C. The yield was determined by
weighing the dried solids and dividing this weight by the weight of
the initial synthesis mixture. The so-calculated yield was about
6.9 wt%. The phase purity of the sample was determined by X-ray
diffraction and was characterized substantially by the d-spacings
shown in Table 1 above. An SEM micrograph was recorded (FIG. 13),
and the crystal size was determined, on average, to be about 0.3
.mu.m or smaller.
Examples 7-13
[0108] A series of samples was made according to the same procedure
as Example 6, but only changing the Si/Al.sub.2 ratio of the
synthesis mixture. All products resulted in materials characterized
substantially by the d-spacings shown in Table 1 above, with an
average crystal size of about 0.4 .mu.m. The yield results are
summarized in Table 2.
TABLE-US-00002 TABLE 2 Yield of products made using TEOS according
to Examples 6-13 with a heat-up rate of about 40.degree. C./hr and
various Si/Al.sub.2 ratios in the mixture. Example Si/Al.sub.2
Yield % 6 0.11 6.9 7 0.12 8.0 8 0.13 8.2 9 0.14 9.2 10 0.15 9.8 11
0.16 10.3 12 0.17 10.6 13 0.18 10.1
Example 14
[0109] A synthesis mixture having a molar composition of about 0.11
SiO.sub.2:P.sub.2O.sub.5: Al.sub.2O.sub.3:2 DMCHA:40 H.sub.2O, as
well as 400 wt ppm seeds, was prepared according to the following
procedure. A solution of phosphoric acid was prepared by combining
phosphoric acid [Acros, 85%] and water. To this solution was added
the appropriate amount of Condea Pural SB [Sasol, 75.6 wt %
Al.sub.2O.sub.3], and the slurry was stirred for about 1 hour at
about 10.degree. C. To this mixture was added the appropriate
amount of tetraethylorthosilicate [TMOS, 99%, from Fluka]. This
mixture was then aged at about 10.degree. C. while stirring for
about another one hour. Then the appropriate amount of
dimethylcyclohexylamine [DMCHA, 99%, from Purum Fluka] was added.
This mixture was stirred for about 10 minutes before the seeds
(SAPO-34 seeds) were added. The final mixture was transferred to an
autoclave which was heated, while stirring, to about 160.degree. C.
with a heat-up rate of about 40.degree. C./hr. After about 144
hours this temperature, the autoclave was cooled to approximately
room temperature, and the solids were washed with demineralized
water and dried at about 120.degree. C. The yield was determined by
weighing the dried solids and dividing this weight by the weight of
the initial synthesis mixture. The so-calculated yield was about
8.6 wt %. The phase purity of the sample was determined by X-ray
diffraction and was characterized substantially by the d-spacings
shown in Table 1 above. An SEM micrograph was recorded (FIG. 14),
and the average crystal size was determined to be about 0.3 .mu.m
or smaller.
Examples 15-21
[0110] A series of samples was made according to the same procedure
as Example 14, but only changing the Si/Al.sub.2 ratio of the
synthesis mixture. All products resulted in materials characterized
substantially by the d-spacings shown in Table 1 above, with an
average crystal size of about 0.3 .mu.m. The yield results are
summarized in Table 2.
TABLE-US-00003 TABLE 3 Yield of products made using TMOS according
to Examples 14-21 with a heat-up rate of about 40.degree. C./hr and
various Si/Al.sub.2 ratios in the mixture. Example Si/Al.sub.2
Yield % 14 0.11 8.6 15 0.12 9.0 16 0.13 9.1 17 0.14 10.0 18 0.15
10.6 19 0.16 11.3 20 0.17 11.9 21 0.18 12.5
Example 22
[0111] A synthesis mixture having a molar composition of about 0.15
SiO.sub.2:P.sub.2O.sub.5: Al.sub.2O.sub.3:2 DMCHA:40 H.sub.2O, as
well as 400 wt ppm seeds, was prepared according to the following
procedure. A solution of phosphoric acid was prepared by combining
phosphoric acid [Acros, 85%] and water. To this solution was added
the appropriate amount of Condea Pural SB [Sasol, 75.6 wt %
Al.sub.2O.sub.3], and the slurry was stirred for about 1 hour at
about 10.degree. C. To this mixture was added the appropriate
amount of tetraethylorthosilicate [TEOS, 98%, from Aldrich]. This
mixture was then aged at about 10.degree. C. while stirring for
about another one hour. Then the appropriate amount of
dimethylcyclohexylamine [DMCHA, 99%, from Purum Fluka] was added.
This mixture was stirred for about 10 minutes before the seeds
(SAPO-34 seeds) were added. The final mixture was transferred to an
autoclave which was heated, while stirring, to about 170.degree. C.
with a heat-up rate of about 40.degree. C./hr. After about 24 hours
this temperature, the autoclave was cooled to approximately room
temperature, and the solids were washed with demineralized water
and dried at about 120.degree. C. The yield was determined by
weighing the dried solids and dividing this weight by the weight of
the initial synthesis mixture. The so-calculated yield was about
11.8 wt %. SEM micrographs were recorded, and the crystal size was
determined, on average, to be about 0.5 .mu.m or smaller. The
Si/Al.sub.2 ratio in the recovered product was determined to be
about 0.23. The product sieve of Example 22 was pelletized and
calcined at about 600.degree. C. for about 4 hours in air, and was
then tested for its methanol-to-olefins (MTO) conversion
performance under the following conditions: reaction temperature of
about 500.degree. C.; WHSV of about 100 g MeOH/g sieve/hr; and
total pressure of about 25 psig (about 273 kPag). The average prime
olefin selectivity (POS) was determined to be about 77.8 wt %.
Comparative Example C1
[0112] A synthesis mixture having a molar composition of about 0.15
SiO.sub.2:P.sub.2O.sub.5:Al.sub.2O.sub.3:2 DMCHA:40 H.sub.2O, as
well as 100 wt ppm seeds, was prepared according to the following
procedure. A solution of phosphoric acid was prepared by combining
phosphoric acid [Acros, 85%] and water. To this solution was added
the appropriate amount of Condea Pural SB [Sasol, 75.6 wt %
Al.sub.2O.sub.3], and the slurry was stirred for about 1 hour at
about 10.degree. C. To this mixture was added the appropriate
amount of Ludox AS40 [ammonium stabilized silica sol containing 40
wt % SiO.sub.2, from Grace NV]. After about 10 minutes, the
appropriate amount of dimethylcyclohexylamine [DMCHA, 99%, from
Purum Fluka] was added. This mixture was stirred for about 10
minutes before the seeds (SAPO-34 seeds) were added. The final
mixture was transferred to an autoclave which was heated, while
stirring, to about 170.degree. C. with a heat-up rate of about
20.degree. C./hr. After about 48 hours this temperature, the
autoclave was cooled to approximately room temperature, and the
solids were washed with demineralized water and dried at about
120.degree. C. The yield was determined by weighing the dried
solids and dividing this weight by the weight of the initial
synthesis mixture. The so-calculated yield was about 16.5 wt %. SEM
micrographs was recorded, and the crystal size was typically about
2 .mu.m or larger. The Si/Al.sub.2 ratio in the recovered product
was determined to be about 0.15. The product sieve of Comparative
Example C1 was pelletized and calcined at about 600.degree. C. for
about 4 hours in air, and was then tested for its
methanol-to-olefins (MTO) conversion performance under the
following conditions: reaction temperature of about 500.degree. C.;
WHSV of about 100 g MeOH/g sieve/hr; and total pressure of about 25
psig (about 273 kPag). The average prime olefin selectivity (POS)
was determined to be about 76.5 wt %.
[0113] As can be seen from the above Examples and Comparative
Examples, organic silicon sources (e.g., alkoxy-functional
silicates) demonstrate a distinct advantage over inorganic silicon
sources (e.g., colloidal silica) in both crystal size and POS (for
methanol-to-olefins reactions), though the sieve formation yields
are not as high. Further, among organic silicon sources, TMOS
advantageously shows slightly higher sieve formation yields with
relatively similar (or slightly smaller) crystal sizes. A graphical
comparison of the yield vs. Si/Al.sub.2 ratio in synthesis mixture,
taken from Tables 2-3, is presented in FIG. 5.
[0114] While the present invention has been described and
illustrated by reference to particular embodiments, those of
ordinary skill in the art will appreciate that the invention lends
itself to variations not necessarily illustrated herein. For this
reason, then, reference should be made solely to the appended
claims for purposes of determining the true scope of the present
invention.
* * * * *